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Small aluminum container
(imgur.com)
Let us help you identify that mysterious object you’ve found.
Currently in CHALLENGE mode: If you've got something obscure knocking about, post a picture, and let's see how we do. Please prefix such posts with "CHALLENGE:" so we know we've got a fighting chance.
My wild guess would be two end stops for pipes. One external and internally treaded for the same diameter.
That's what they are! I have a box full of leftover parts from years of home repairs, and I frequently store caps of opposite genders screwed together like this.